Add 'therubyracer' as javascript runtime for asset compilation.

Gemfile

@@ -26,6 +26,9 @@ gem 'carrierwave'
 # We are sending mail. The latest version is just fine.
 gem 'mail'
 
+# See https://github.com/sstephenson/execjs#readme for more supported runtimes
+gem 'therubyracer', platforms: :ruby
+
 # To use debugger (ruby-debug for Ruby 1.8.7+, ruby-debug19 for Ruby 1.9.2+)
 # gem 'ruby-debug'
 # gem 'ruby-debug19', :require => 'ruby-debug'

Gemfile.lock

@@ -60,6 +60,7 @@ GEM
       railties (>= 3.0, < 5.0)
       thor (>= 0.14, < 2.0)
     json (1.8.1)
+    libv8 (3.16.14.3)
     mail (2.5.4)
       mime-types (~> 1.16)
       treetop (~> 1.4.8)
@@ -90,6 +91,7 @@ GEM
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
     rake (10.1.0)
+    ref (1.0.5)
     sass (3.2.12)
     sass-rails (4.0.1)
       railties (>= 4.0.0, < 5.0)
@@ -104,6 +106,9 @@ GEM
       actionpack (>= 3.0)
       activesupport (>= 3.0)
       sprockets (~> 2.8)
+    therubyracer (0.12.0)
+      libv8 (~> 3.16.14.0)
+      ref
     thor (0.18.1)
     thread_safe (0.1.3)
       atomic
@@ -135,4 +140,5 @@ DEPENDENCIES
   pg
   rails (= 4.0.1)
   sass-rails
+  therubyracer
   uglifier